@Carlo5058
The community for Italian language is: Community Italiano
If your tennant is illegally offers your appartment on Airbnb, then this is a matter between you and your tennant. Airbnb does warn new host to obey laws and rules, but is not responsible if they do not.
The only thing you can do is report the listing to Airbnb (via "report" link). Airbnb does not check who owns the accommodation or if there are special rules.
You mentioned already having terminated the renting contract. You could also claim from your tennant the Airbnb income he illegally earned.